On the Critical Ionization Velocity Effect in Interstellar Space and Possible Detection of Related Continuum Emission

Abstract

Interstellar neutral hydrogen (HI) emission spectra manifest several families of linewidths whose numerical values (34, 13 & 6 km/s) appear to be related to the critical ionization velocities (CIVs) of the most abundant interstellar atomic species. Extended new analysis of HI emission profiles shows that the 34 km/s wide component, probably corresponding to the CIV for helium, is pervasive. The 34 km/s wide linewidth family is found in low-velocity (local) neutral hydrogen (HI) profiles as well as in the so-called high-velocity clouds. In addition, published studies of HI linewidths found in the Magellanic Stream, Very-High-Velocity Clouds, and Compact High-Velocity Clouds, all of which are believed to be intergalactic, have noted that typical values are of the same order. If the critical ionization velocity effect does play a role in interstellar space it may be expected to produce locally enhanced electron densities where rapidly moving neutral gas masses interact with surrounding plasma. Evidence is presented that suggests that this phenomenon is occurring in interstellar space. It manifests as a spatial association between peaks in HI structure offset with respect to peaks in high-frequency radio continuum data obtained with the Wilkinson Microwave Anisotropy Probe.

To be published in IEEE Trans. Plasma Sci. Aug 2007

References in corpus (7)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis
• HIPASS High-Velocity Clouds: Properties of the Compact and Extended Populations
• Highly Ionized Gas Surrounding High Velocity Cloud Complex C
• Detection of H-alpha emission from the Magellanic Stream: evidence for an extended gaseous Galactic halo
• High Galactic Latitude Interstellar Neutral Hydrogen Structure and Associated (WMAP) High Frequency Continuum Emission
• The critical velocity effect as a cause for the Hαemission from the Magellanic stream

Cited by in corpus (2)

• High Galactic Latitude Interstellar Neutral Hydrogen Structure and Associated (WMAP) High Frequency Continuum Emission
• On the Apparent Associations between Interstellar Neutral Hydrogen Structure and (WMAP) High Frequency Continuum Emission